不要在循环中操作数据库(案例)

各位在写代码的时候千万不要在循环中对数据库进行操作,这样会大大降低数据库的性能,今天在写接口的时候碰到了这种情况,被组长说了一下,于是改了改,代码奉上:

    @Override
    public List<ScrInspectionVo> selectByMcId(String id) {
        List<ScrInspectionVo> inspectionVos = this.list(new LambdaQueryWrapper<ScrInspection>()
                        .eq(ScrInspection::getMcId,id)
                        .orderByDesc(ScrInspection::getSort))
                .stream()
                .map(scrInspection -> {
                    ScrInspectionVo scrInspectionVo = new ScrInspectionVo();
                    scrInspectionVo.setId(scrInspection.getId());
                    scrInspectionVo.setMcId(scrInspection.getMcId());
                    scrInspectionVo.setItemId(scrInspection.getItemId());
                    scrInspectionVo.setStatus(scrInspection.getStatus());
                    scrInspectionVo.setCreateTime(scrInspection.getCreateTime());
                    scrInspectionVo.setSort(scrInspection.getSort());
                    scrInspectionVo.setType(scrInspection.getType());
                    scrInspectionVo.setCreateBy(scrInspection.getCreateBy());
                    //项目筛查数据处理
                    if (scrInspection.getType().equals(ScreeningConst.PROJECT_SCREENING)){
                       //根据检查项目id查询检查项目名称
                        CheckItemTreeVO checkItemTreeVO = remoteKnowledgeApi.selectOne(scrInspection.getItemId(), SecurityConstants.FROM_IN);
                        scrInspectionVo.setInspectionName(checkItemTreeVO.getClassifyName());
                    }
                    //流调筛查数据处理
                    if (scrInspection.getType().equals(ScreeningConst.EPIDEMIC_SCREENING)){
                        List<ScrInspectionQuestionVo> scrInspectionQuestionVos = this.selectByQuestionList(ScreeningConst.EPIDEMIC_SCREENING);
                        scrInspectionQuestionVos.stream().forEach(s->{
                            scrInspectionVo.setInspectionName(s.getTextName());
                        });
                    }
                    return scrInspectionVo;
                }).collect(Collectors.toList());

        return inspectionVos;

其中selectByQuestionList和selectOne方法都是调用的其他服务的,全是在循环中调用的接口,这样对于数据库来说的话会有很大压力,所以经过我的整改,写了两个方法,代码奉上:

  @Override
    @ConverData(serviceId = ServiceNameConstants.KNOWLEDGE_SERVICE, table = "knowledge_check_item", key = "itemId", dbKey = "id", dbValue = "classify_name", value = "inspectionName")
    public List<ScrInspectionVo> selectByMcId(String id) {
        //根据医联体id查询出医联体下的所有数据
        List<ScrInspection> scrInspections = this.list(new LambdaQueryWrapper<ScrInspection>()
                .eq(ScrInspection::getMcId, id)
                .orderByDesc(ScrInspection::getSort));
        //项目筛查
        List<ScrInspection> project = scrInspections.stream()
                .filter(x -> x.getType()==1).collect(Collectors.toList());
        //流调筛查
        List<ScrInspection> epidemiological= scrInspections.stream()
                .filter(liu -> liu.getType()==0).collect(Collectors.toList());

        List<ScrInspectionVo> projectList = initPro(project);
        List<ScrInspectionVo> epList = initEp(epidemiological);

        List<ScrInspectionVo> vos = new ArrayList<ScrInspectionVo>(projectList);

        vos.addAll(epList);
        return vos;
    }

    List<ScrInspectionVo> initPro(List<ScrInspection> pro){
        if (CollUtil.isEmpty(pro)){
            return new ArrayList<>();
        }
        return pro.stream().map(p->{
            ScrInspectionVo scrInspectionVo = new ScrInspectionVo();
            BeanUtils.copyProperties(p,scrInspectionVo);
            return scrInspectionVo;
        }).collect(Collectors.toList());
    }

    List<ScrInspectionVo> initEp(List<ScrInspection> epidemiological){
        if (CollUtil.isEmpty(epidemiological)){
            return new ArrayList<>();
        }
        //获取到itemId列表
        List<String> epIds = epidemiological.stream().map(ScrInspection::getItemId).collect(Collectors.toList());
        FormListModel formListModel = new FormListModel();
        formListModel.setFormKeys(epIds);
        //返回问卷列表
        List<FormListVO> epList = remoteMessageApi.getFromList(formListModel, SecurityConstants.FROM_IN).getData();
        List<ScrInspectionVo> scrInspectionVos = epidemiological.stream().map(s -> {
            ScrInspectionVo scrInspectionVo = new ScrInspectionVo();
            BeanUtils.copyProperties(s, scrInspectionVo);
            for (FormListVO formListVO : epList) {
                if (s.getItemId().equals(formListVO.getFormKey())){
                    scrInspectionVo.setInspectionName(formListVO.getTextName());
                }
            }
            return scrInspectionVo;
        }).collect(Collectors.toList());
        return scrInspectionVos;
    }

先根据mcId查询出所有数据,然后对这些数据根据条件进行分组,然后自己写两个方法,这样就避免了在循环中重复调用方法,其中initPro和initEp就是我写的两个方法